Although Prowse inhabited Darth Vader's mask and cloak for the three films, doing all of the striding, pointing, telekinetic strangling etc., the voice of the character was famously provided by James Earl Jones. However, when shooting the first Star Wars movie (then called Star Wars, now known as A New Hope), Prowse was not informed that his voice acting talents would not be required. Accordingly, he learned all of Vader's lines, and presumably put a great deal of effort into determining the his character's motivation in delivering lines such as "There will be no-one to stop us this time". It was some time into the shoot before Prowse discovered, accidentally, that George Lucas never intended to use Prowse's broad west country tones as the vocal personification of all evil. It is not known whether he subsequently bothered to learn the lines for The Empire Strikes Back and Return of the Jedi.

A further insult was to await him on this last film, however, when a third actor, Sebastian Shaw, was called upon to play the unmasked Vader in the final scenes. Neither was the six-foot, six-inches tall Prowse asked to portray the young Anakin Skywalker in The Phantom Menace, although one presumes this decision was less galling to the actor.

I will omit a full filmography, which can be found at IMDB, but I will note the following items of trivia:

dokool provides the following tidbit: "he's gone on record as saying that he wants to re-don the suit for Episode 3, and that since his last knee surgery he's been in intensive training." - You heard it here first! Probably.